NASA Study: Climate Sensitivity Is High So ‘Long-Term Warming Likely To Be Significant’

A new NASA study suggests that projections of Earth’s future warming should be more in line with previous estimates that indicated a higher sensitivity to increasing greenhouse gas emissions. (Credit: NASA)

Yet another new study finds the climate’s sensitivity to carbon pollution is on the high side. That means, absent rapid reductions in greenhouse gases, global warming is likely to be high enough to destroy a livable climate.

This is consistent with a January Nature study on climate sensitivity, which found we are headed toward a “most-likely warming of roughly 5°C [9°F] above modern [i.e. current] temperatures or 6°C [11°F] above preindustrial” temperatures this century.

This finding is also consistent with paleoclimate data (see “Last Time CO2 Levels Hit 400 Parts Per Million The Arctic Was 14°F Warmer!”). Also, this study is consistent with other recent observation-based analyses (see “Observations Support Predictions Of Extreme Warming And Worse Droughts This Century”).

And this study throws yet more cold water (hot water?) on some claims that the climate’s sensitivity is on the low side, claims that have been widely challenged and perhaps fatally undermined by the most recent studies.

Global temperatures have increased at a rate of 0.22 °Fahrenheit (0.12 °Celsius) per decade since 1951. But since 1998, the rate of warming has been only 0.09°F (0.05°C) per decade — even as atmospheric carbon dioxide continues to rise at a rate similar to previous decades. Carbon dioxide is the most significant greenhouse gas generated by humans.

Some recent research, aimed at fine-tuning long-term warming projections by taking this slowdown into account, suggested Earth may be less sensitive to greenhouse gas increases than previously thought. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which was issued in 2013 and was the consensus report on the state of climate change science, also reduced the lower range of Earth’s potential for global warming.

To put a number to climate change, researchers calculate what is called Earth’s “transient climate response.” This calculation determines how much global temperatures will change as atmospheric carbon dioxide continues to increase — at about 1 percent per year — until the total amount of atmospheric carbon dioxide has doubled. The estimates for transient climate response range from near 2.52°F (1.4°C) offered by recent research, to the IPCC’s estimate of 1.8°F (1.0°C). Shindell’s study estimates a transient climate response of 3.06°F (1.7°C), and determined it is unlikely values will be below 2.34°F (1.3°C).

It is worth noting that absent sharp CO2 reductions, we are headed toward a tripling of atmospheric CO2 levels this century, or even higher, which will lead to amplifying feedbacks (like carbon emissions from the defrosting permafrost) and almost unimaginable increases in temperature.

Michael Mann, one of the country’s top climatologists (who did not contribute to the paper), called the study “extremely important” and said it contains two especially key findings. First, the cooling effect of sulfate aerosols in recent decades may have been underestimated. Second, the concept of TCR may be flawed. Both findings point to the fact that the threat of future warming may have been underestimated, Mann said. “As shown in this article,” Mann said, “transient climate response doesn’t adequately distinguish between the short-term cooling effects of sulfate aerosols (which can disappear quickly) and the long-term, committed warming from carbon dioxide emissions which last in the atmosphere for centuries and beyond.”

So while we may have seen a slowdown in recent surface temperature warming — though not in ocean warming or glacial melt — future warming remains likely to be on the high side, if we stay on our current emissions pathway.

“I wish we could take some solace from the slowdown in the rate of warming, but all the evidence now agrees that future warming is likely to be towards the high end of our estimates so it’s more clear than ever that we need large, rapid emissions reductions to avoid the worst damages from climate change.”

The science is clear. The solutions are here. It’s time for the political will to appear.

The science is clear, therefore, closed cycle nuclear energy must be used to power the world because it is intrinsically the least expensive, most abundant and safest way to prevent fossil fueled depletion into an overheated biosphere. Nuclear lasts longer, provides actual baseload and could provide for the high process heat necessary for powering a planetary civilization.I like efficiency but don’t want energy rations, more pollution and very expensive gasoline for my kids. Let’s get rid of coal pollution once and for all and promote meltdown proof nuclear reactors.

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MemeMine

March 16, 2014 13:27

Who should we trust; climate change “believers” or the scientists that are 95% certain that we need to save the planet from Human CO2? Will it be to late to stop unstoppable warming when they are finally 100% certain that the end is near for billions of innocent children doomed to an unavoidable climate crisis?Only science can determine certainty for the worst crisis imaginable.